I thought it'd be cool for me to cheat and have little Charmander come out in unkown territory .3.
But first I'd like to know if it was possible.
EDIT: Mystery Zone is like in the walls where you normally can't get without cheating, FYI.
I hatched an egg and then after that, EVERYTHING changed. The ground was made of white circles on black ground, and tons of other crazy crap that made it look like a 3 year old edited the tileset... yeah... Normally, it's not possible to open the menu in a Mystery Zone, but if you hatched an Egg there and returned to another location, the tileset adapts to an unused one associated with the Mystery Zone. (mentioned in the glitches caused section). This tileset also exists within HeartGold and SoulSilver, and it's basically like a placeholder tileset where every object is white.
[Bulbapedia][1]
Yes, you can. [1]: http://bulbapedia.bulbagarden.net/wiki/Talk:Mystery_Zone#Platinum_egg_hatch.21.21